The present invention relates to power actuated tools for driving fasteners into a substrate, and more particularly to such tools which operate by detonation of an explosive charge.
Power actuated tools for driving fasteners such as nails or pins, into a substrate such as a concrete or steel beam, conventionally comprise a barrel from which the fastener is expelled by means of a piston driven by detonation of an explosive charge.
In power actuated tools of this general type, the power output of the tool can be controlled by utilising explosive charges of different power. Alternatively a variable power adjustment system may be incorporated into the tool itself. Such power adjustment systems may operate by altering the volume of the firing chamber defined in the barrel of the tool rearwardly of the piston, or by controlled venting of combustion gases from the portion of the barrel rearwardly of the piston. The present invention relates to an improved power adjustment system which operates by providing a controlled venting of the combustion gases.